*3.1.5. Avoiding exposure to direct sunlight*

Direct exposure of sunlight results in the killing of antigen present in the vial; as a result, the titer of vaccine antigens are reduced in the vaccine and it may become ineffective. During formulation of solution for oral or parental vaccines, direct exposure to sunlight should be avoided and for oral vaccines the cap of the vaccine vial should be opened inside water. The vaccines should be mixed in drinking water in a room or in a shady place; moreover, during the transportation of vaccine, black or colored bags and cartons should be used to prevent sunlight affecting the vaccine.
